How can I determine if the radio is enabled or disabled on AP?

Go to the Monitor Device Menu options, by Monitor → Access Points → Devices. The current radio settings are shown in the Channel column. The first number corresponds to 2.4GHz channel, and the second number corresponds to 5GHz channel. If one of the radio is disabled, it will be shown as a dash(-). If you do not see the Channel options, click on the option and tick the Channel checkbox.